Below is an initial read-out of the key messages from TOTeM45:
- Global growth of gas-fired power generation as complement to renewables
- 23% of global 25,600 TWh from gas, 1.6% increase in 2017 (7.6% decrease in USA counterbalanced by 4.6% growth in rest of world – particularly China, EU, SE Asia)
- So why reluctance for GT research support?
- Challenges in terms of flexibility, transient response, etc.
- Currently no real driver for CCS on GTs from industry – carbon price too low, financial case?
- Combustion dynamics (CD) are a significant issue
- Dual-fuel (liquid/gas) flexible systems also required
- Different methods (e.g. axial) for ‘staged’ combustors, with strengths/weaknesses
- Different industrial staging designs e.g. EV Burner (Alstom) , SWOZZLE (GE)
- Swirl, vortex breakdown integral
- GT cycles increasing temperature for efficiency -> increased NOx?
- Near-term R&D priorities: Additive manufacture; model-based control (sensors, artificial intelligence, ‘big data’); enhanced prediction of CD
GTs for flexible power (operational and fuels flexibility):
- How far can we get with simplified lower-order network model + flame describing function (FDF) models for CD?
- Validation: Encouraging/surprising! (EM2C, Camb, Siemens, …) to date -> more experimental (optical) validation required
- Predictability sufficient for industry purposes?
- How to calculate FDFs ‘accurately enough’?
- Four-step chemistry sufficient (for industry?) – to be confirmed
- Active/feedback control? Response time?
- New fuels (H2, NH3) will also suffer from CD
- Plea for industry to vocally support research funding applications in the field
- Problems in predicting CD, even when Wobbe Index (WI) is ‘in spec’, C2+?) ->
- Additional combustion /fuel parameters required. What? Methane Number?
- OEMs have developed control systems but they are expensive – cheaper options?
- Heading towards >20% H2 in gas grids. Issues?
- New burners are now designed to avoid flashback
- ‘Permutation Entropy’ for predicting CD onset – 1s response
- Other ‘relatively cheap’ techniques, including laser-induced breakdown spectroscopy (LIBS) and chemiluminescence (CL), being developed for non-intrusive burner diagnostics – how much optical access practicable?
GTs for ‘storage-to-power’:
- H2 in gas system variety of sources (syngas/CCS, green H2,…)
- Changes required in combustion; materials/cooling; turbo
- WI variation insufficient: what in addition?
- New combustion systems required for high-H2 fuels?
- Promising ‘FLOX’ (flameless combustion) system claimed capable of burning H2 with high fuel/operational flexibility and low emissions
- What is and what isn’t FLOX?
- Staged combustion autoignition showed operational window for high-H2 operation
- H2 energy transportation -> case for ammonia (NH3)?
- Established challenges for NH3: economics ; NH3 emissions; NOx; public acceptance
- Various methods for reducing NOx recently demonstrated in Wales and Japan (RQL; humidified; operational pressures;..)
- Existing research tools enable ammonia combustion optimisation. Needs funding to keep UK competitive
GTs for safe, decarbonised power:
- Exhaust gas recirculation (EGR) required for post-combustion CO2 capture on GTs
- O2 will limit the degree of EGR achievable
- Oxyfuel CCS GT promising but need turbomachinery and combustor developments
- Oxyfuel with 1st generation burners shows good stability, but lots of challenges for development e.g. CO emissions
- Various ways of adapting GT operation for improving CCS efficiency. But what is the optimum combination?
- Advanced solvents for post-combustion capture
- System integration and whole systems analysis required
- Social science, public perception, risk/safety for CCS
- H2 safety still requires attention: ignition, DDT potential, …
- How best to mitigate scenarios like flame-out, H2 jet in hot environment
- Are H2 explosion/detonation scaling sufficient? Geometries?
Additive manufacturing and advanced materials:
- Considerable GT materials info, but often poorly characterised experimentally
- ‘Open Access’ materials database proposed (by ETN?): IFRF should link and promote
- Higher operating conditions …-> materials development needs
- Additive layer manufacturing (ALM) is a potential ‘game changer’
- ALM has key role for GTs in terms of enabling better thermal management and lightweighting
- Most OEMS have active ALM programmes
- ALM gives potential to design and manufacture high-temperature components which couldn’t be delivered with traditional techniques
- Enables reduction of materials utilised and significant incremental efficiency improvement mitigates/eliminates cost differential with traditional techniques
- Several examples of components built for high-end markets (e.g. F1, etc.) from likes of HEITA (eg. LT and HT HEXs, turbomachinery, fuel and combustion components
- Up to 50% weight reduction achieved. Metal temperatures reduced by up to 220degC, enabling turbines to run hotter
- Could there be a role as proposed collective database for ALM future development?
- Expect to see considerable development in this field, challenges include surface finishing.